As a next-generation wireless communication system, a wireless communication system that uses a high frequency band such as millimeter waves (mmW) is considered to support high capacity data services. Since the communication distance between a subscriber station and a base station is reduced in a system using a high frequency band, the cell radius of a base station becomes smaller. Accordingly, the number of base stations installed to secure a service area of a subscriber station increases. Further, considering the mobility of a subscriber station, if the cell radius of base stations decreases and the number of the base stations increase, then the number of handovers between cells of the subscriber stations and the overhead of the system also increases, due to the handover of the subscriber station.
In a wireless communication system using a high frequency band, since the number of base stations per unit area increases, serving base stations communicating with a subscriber station are frequently changed during the movement of the subscriber station, and verification procedures for creating and allocating verification keys and security keys for transmitting and receiving data between the changed base station and the subscriber terminal are required whenever the serving base stations are changed.
Thus, a measure for efficiently performing a verification procedure is required in a wireless communication system using a high frequency band. In particular, in understanding the operation of servicing a subscriber station in order to minimize the overhead of changing base stations in a wireless communication system through the cooperation of many base stations around the terminal, efficiently performing a verification procedure and security key management necessary for performing cooperation communications with at least one of the base stations is required.